cpuset: remove unneeded NODEMASK_ALLOC() in cpuset_attach()

oldcs->mems_allowed is not modified during cpuset_attach(), so we don't
have to copy it to a buffer allocated by NODEMASK_ALLOC().  Just pass it
to cpuset_migrate_mm().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4683fe728c9b..7f384f4013b2 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1438,10 +1438,9 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
         struct mm_struct *mm;
         struct cpuset *cs = cgroup_cs(cont);
         struct cpuset *oldcs = cgroup_cs(oldcont);
-        NODEMASK_ALLOC(nodemask_t, from, GFP_KERNEL);
         NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL);
 
-        if (from == NULL || to == NULL)
+        if (to == NULL)
                 goto alloc_fail;
 
         if (cs == &top_cpuset) {
@@ -1463,18 +1462,16 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
         }
 
         /* change mm; only needs to be done once even if threadgroup */
-        *from = oldcs->mems_allowed;
         *to = cs->mems_allowed;
         mm = get_task_mm(tsk);
         if (mm) {
                 mpol_rebind_mm(mm, to);
                 if (is_memory_migrate(cs))
-                        cpuset_migrate_mm(mm, from, to);
+                        cpuset_migrate_mm(mm, &oldcs->mems_allowed, to);
                 mmput(mm);
         }
 
 alloc_fail:
-        NODEMASK_FREE(from);
         NODEMASK_FREE(to);
 }